I'm afraid you cannot escalate the matter with eBay, they are not refusing to help, just acting withing the parameters of their 30 day MBG policy , they cannot help,  you are out of time there , and sadly out of time with your payment provider.

Was this a purchase from a UK registered seller, who offered some longer guarantee which they are now not upholding?  Then,  turn to Citizens advice for any further steps you can take here.

@garet_92