Vsc light on, Master triangle on & can't accelerate!

Long-term parking is not very good.
The high-voltage battery modules can discharge.
Self-discharge varies for different modules and when one has dropped significantly in voltage, the others may remain normal.
When operating a hybrid system, these differences in the voltage of neighboring modules can cause a red triangle and failure messages.

To answer your questions accurately, we need some data on the error codes.
Do you or your husband have the opportunity to find a scanner to read the codes?

 

The easy over revving of your engine is the clue your electric motors aren't meshing well with your gas engine and the engine rev sound happens like the clutch is slipping your clutch is your electric motor if you will and when it can't actively participate like it wants to your engine will outreve your electric motor I guess is what I'm looking to say kind of happened on my '09 and when this started to happen the traction battery was going into the toilet quickly. After changing the battery for a new one that problem went away forever. Then I got another '07 car drove that for a while still have the '09 '07 started doing the same thing same problem traction battery just not up to snuff fix that all that revving and slipping vanished The red car on your MFD could be telling you that you're not getting adequate charging because your inverter pump is not working or up to snuff but even if you're charging near end of life battery like crazy you can still get the slipping and the over revving so you may have a compound set of problems in that case

 

aaa doesn't know anything about hybrid cars.
There is no power surge when jumping the 12v battery.

How old is the 12v battery? You could charge it for 6 or more hours at
5 amps or less. Remove the charger and check the voltage about 30 minutes later.
It should read 12.6 or more. Anything less it's marginal. If the battery is older than 6 years,
it probably time to replace it.

Is the hybrid battery the original for your 2012 Prius? It could be getting weak.
You can use a proper hybrid code reader and clear all the codes. Start the car and just
let it idle and charge up the battery. With no heavy load it "may" charge up the battery and
balance out the blocks some.

It probably wouldn't hurt to get the Prolong system, or one similar, and run the hybrid battery
through the complete cycles to bring some life back to the hybrid battery. It worked for me for
about 3 years.

Even if you just got the charger you could charge it for several hour after it levels out to balance
all the blocks.

You also need to check the inverter coolant pump, it might be failing and not circulating the coolant
and causing the inverter to over heat. And also check the inverter because it might have failed.

If you can't do these checks yourself, you should take it to a place they works with hybrid cars.
And a Prius specialist would be best...

 

lights on the dash mean that there are trouble codes that can be read at the dealer or a qualified hybrid mechanic with a prius aware code reader.
these codes will point the way to the fault(s) and we can help with diagnosis and repair if you post them here.

 

Depending on your mechanic's level of expertise; I wouldn't recommend second hand batteries off of flea-bay. They are usually batteries salvaged from wrecks or from other battery packs that has failed. You may even get an older battery than you currently have.
Crack the traction battery case and check for corrosion on the battery's power bus. Clean or replace and go from there. The Dr. Prius app can give you an idea of the location of bad modules, but a physical exam is in order. Hopefully it's something simple. These types of cars were produced to be driven, long idle periods can actually damage the car.
I'm not familiar with the cost of a traction battery in the UK - but you'll need to do your "homework" on what you can afford vs reliability vs warranty time for a rebuilt pack. If your buying a new traction pack, you can usually count on another 10 years of trouble-free operations of that traction pack. That's assuming that nothing else goes wrong with the car...

Good Luck and hope this helps.....

 

7e8, 7ea, and 7eb look like the addresses of different ECUs in the car that were queried for codes. The actual trouble codes are five characters long, where the first is a letter P, C, B, or U and the second is a 0, 1, 2, or 3.

It's good to say what the actual code is, though if "replace hybrid/ev battery pack" is what the description said, then P0A80 was probably the code.