Telkom issues

I am so frustrated with Telkom. I paid my bill in early December but by mistake used an incorrect account number (I used to have 2 telkom lines with 2 different accounts but amalgamated them but and now have 1 account number but when I pay via eft it automatically reverts to the old account number and I have to manually change it). I have been phoning telkom once a week ever since to try and get the correct account credited to no avail. I get given reference numbers but then get told the following week when I phone back that nobody logged the call. I am back to square one and am pulling my hair out. How on earth do I sort this out?