Unreachable contact centre service

I have been an MWEB customer since around 1995. I currently have a fibre contract (FTTH) with MWEB after many years on ADSL. Fibre and ISP service is pretty good BUT reaching the MWEB contact centre to amend/upgrade a contract is a nightmare. It seems impossible to reach a sales agent (after 5 attempts by phone and much wasted time waiting). I am trying to transfer my service from existing premises to a new home and simply cannot reach anyone to advise on how to go about this. Looks like cancelling the contract online and applying for a new one online is the only way. But then why not look for another ISP. Is this what MWEB wants to drive existing customers to do, just to speak to someone? Is there no way of addressing a sales centre via email?