RCS Financial Service Provider (Part of Builders Warehouse)

I must say, RCS Financial Service Provider is quick to take your money each month but are not there to assist you in anyway. I have logged an issue I have with my app, I have been struggling for almost 2 years but I cannot even get a phone call. My previouis email was no longer in use so I had to change which I did, ended up going in store cause doing it telephonicly was just impossible, so now I'm receiving all emails correctly but my app doesn't allow me to use my new email address as it requires to send a pin which will only send it to the old mail which no longers exists . If I want to create a new profile it says "I" already exist therefore I cannot enter my new email address. I have logged this call two days ago, no reply no telephone call, nothing, How will I get RCS to connect with me? All I want is just for me to use my new current email address, is that too dificult to ask. Just a matter of changing my email address on your side. as I clearly cannot do it from my side cause there is no option to do so. I am desprately seeking help!!!