No service Telkom outgoing email

Since the 19th October I have experienced difficulty sending emails from any email program on my PC. I get "delivered' followed immediately by :undelivered" so my email is not sent. I have reported to Telkom repeatedly to no avail. They maintain it is an Outlook problem. However my PC guy proved otherwise as it happens on Thunderbird and Live mail. He rang Telkom who could not sort it till I got back home. Sure enough the Telkom guy rang me ( you are not allowed to ring anyone back at Telkom like it is a secret society) he however could not solve it but assured me that his team leader who was at lunch had sorted this problem before and would ring me. That was the 20th December -still waiting. So I reported it again on the 24th December ref ********** 0 and was told that someone would ring me. Still waiting. I am after all paying for this service so would really like it to work after 2 and half months of no service on my outgoing email. I know that Telkom hope by ignoring this I will sign up for Optic Fibre but as a pensioner I cannot.