UberEats - How to Fob-off your customer so you never hear from them again

I would give a ZERO if I could. I ordered the same meal from UberEats at almost the exact time as a friend of mine (we were both at the same location). We both ordered the special (buy-on-get-on-free) from Mochachos in Bosmont. There was an issue with my payment but when it did go through, I realised it had charged me for x2 burgers instead of the special (x1). I raised it via Uber customer service only to be told sorry nothing can be done. No option to reply, provide more info and not even a hint or suggestion that they would investigate. I have tried sending them a follow-up mail but they seem to have discontinued ALL electronic channels which allow you to write feedback (besides the one-off option through the App or website - which comes back with a NO REPLY email. Hence there is no possibility to follow-up on the original complaint. Nice trick if you don't want to hear back from customers - one way communication.