Breach of contract as not receinibg services for the amounts been charged

Have endless issues with the account department. The next issue is that I have upgraded to a 20mbps line 01 October 2019 and only receiving 10mbps as the previous month. But paying for a 20mbps line. So in other words I'm been ****** not only for 10mbs less, but R100 more that what I'm receiving. Accounts department as well as the support are totally clueless.