Shocking Service!!!

I bought my vehicle from We Buy Cars in October 2021, “Category A” Full Dekra report. I drove it two months then left for overseas for three months, got back drove it in March and then took it in for a service, whereby it was noticed a Gear Box problem. Now this is a costly exercise. I have been trying to get hold of We Buy cars since the 31st March, until today (8days later) everyday phoning and pleading for someone to contact me, no joy as at to date I paid cash for my car and do not have this cash to redo a gearbox, which should have not given in, (did not even drive it for 3 month). I do not do long distances (if that 4000km) in total. The car was placed under category A which means that it has no major mechanical issues and is recommended for a quick service check after purchase. I do not have the funds to pay for the repairs, meaning I'm stuck at home with a car I bought a not even 6 months ago, which I can't drive at all, and I've paid the car cash and do not have extra money saved up for these repairs. You can't reach them on the phone. Very quick to accept your money and Pathetic Customer service