Telkom lte poor service

I have a telkom lte mobile wifi service with telkom.and speeds have dropped to 1.5 megabytes per second .i call the center and I am told my speed is limited to 4 MB’s .accirding to the contract .at no time was there any communication about this to me and a friend has the same contract and no limitation .infactvwe took the contract together when it was launched .i had speeds of 60 to 75 MB’s when it started and it has deteriorated to 30 then 10 now to 1,2 to 2,5 MBs,at the call center I get different reasons .first call they said will call me back and Sms me settings in an hour ....nothing was received .i ask for call back again and get someone else with different views and tells me I am on a limited contract.this is total nonsense from telkom,cannot get a straight answer