Terrible after sales service in my opnion

These guys were good to us at the beginning. I don't know kw what the problem is now but their network speed has deteriorated to almost a halt. They just came in after I requested them to come have a look at my speed. When they are here, they claim everything is fine. Immediately when they leave. The network speed goes back to a snails pace. I'm tired of this now. Might be time to find a new isp