How difficult is it to correct an address?!?!

Please could you update my residential/postal address......I've asked so many times for this to be changed and every time I get my statement it's still incorrect. I just spent 16 mins on the phone with your call centre trying to change it where the consultant had no idea what she was doing - how difficult is it to maintain a simple conversation with the client and action a simple request? Please could you get someone competent - who knows how to change an address - to make contact with me urgently. Since inception I've been trying to change this and actually just gave up - but am now in urgent need of proof of residence and need to actually correct this now once and for all.