Telkom LTI

We went over from another service provider to telkom LTI wifi and I must say that in the beginning we had between 15 - 20 mb/s that was not bad, six months down the line, reported several times to telkom about the poor performance, I paying for a 20 mb LTI and I'm not getting even 1 mb/s, very very bad. Thinking of moving to another provider