Stonebridge College / Stonebridge Associated Colleges – chasing cashback payment

I paid my last installment 1st Oct 2019. I completed the course in August 2019. I requested my cashback on the 1st October 2029. My request was ignored. I have requested it again on 4 occasions and still no joy. I was originally told the cash back was £180. Now they claim they said £100. I asked for an email or contact to complain and I was just met with a snotty email saying they were the team who gave me that address to complain.

I paid £319 for a course that doesn't carry any ucas points.