Cancellation & email address transfer not done after 4,5 months (email now not working)

We had fibre installed in June this year (after 4 orders and almost 9 months of waiting even though the neighbourhood installation had been completed and Hellkom had actually ASKED for the order) and therefore wished to cancel a business line ********** 223 which had the previous ADSL account and a landline on it. A formal letter was sent through on the 16 July asking for two email addresses on the account to be transferred to the VOIP number on the fibre line at the same physical address. Since then we have sent through the letter/authorisation TEN TIMES! Each time we have been told by the call centre agent that they WOULD get back to us. It is now the end of November - and NOTHING! (Except that the two email addresses - including our main business email address - have now been stopped!) What do we have to do to get these two very simple issues (email address transfers and an account cancellation) done? Ps. Today I sent through the letter and the company owner IDs for the 11th time - because once again the agent taking the call had NO ACCESS TO PREVIOUS DETAILS.