regarding the error codes, since you already replaced the pump so many times it is possible it is the connector indeed, was the car involved in an accident?
a lot of water gets in that area when you wash the car or it rains, it is better to replace the connector, or it is extremelly likelly it will happen again...
I had an accident years ago, pump burned a year after the accident, fitted a new pump and it lasted 2 months, I replaced the connector after the second time and also did other things, been fine for 5 years now. It was the middle one. although I'm not sure it was because of that, it remais the prime suspect...
(I dont know if the connector was broken in the accident or when they replaced the pump the first time)
Also thank SEAT for this excelent design that it is asking for problems
the connectors need to be sealed or water will find its way inside throwgh the connectors, this is a pump I bought on ebay years ago and came like this...