Loss of service

Here we go again. Can someone from Multichoice please tell me why I can watch DSTV all day and during the night but from 18.00 until maybe 22.00 I keep loosing the signal, i started to have no signal at 18.05 and now it is also at 18.35. If my decoder works during the times mentioned there can not be a problem with the PVR. I just need an answer, Multichoice take my money each month but are not providing their side of the contract. I have had all my connections etc checked by an engineer. Please help Multichoice.