Sorry to hear your bad luck. Been running a MK PC345 last five years - no complaints here but I understand your position.
I had previously run 2 Guest units. First one was a 2 bank which lost one side and was out of warranty. Guest offered me a deal on upgrade and I went with a 3 bank which lasted me 12 years thereabout before lost the crankin bank (lower power- 3 amp). I limped along using a auto charger on the cranker until I finished researching and went with the 345 because Guest had retooled and wasn't sure how they currently stacked up - think they had changed hands or names.
Good luck researching and better luck in your charging future.