Dropped Packets/upstream timeouts for hours in the evenings

After the same last year with no fix, the problem of dropped packets and terrible upstream has returned. It's very frustrating when the family want to relax at the end of the day and watch tv or whatever. 

I'm not saying it's causation, but always when the weather is hot. Against my better judgement the other night I rebooted as instructed in My Virgin Media and we couldn't get it back as it was unable to download config.

I'm so frustrated by the lack of any clear course for resolution with VM. The automated tools are worse than useless and their communication is worse. I asked for texts to tell me when the fault is resolved and each day, on the day quoted for it to be fixed, it just got extended.

think broadband graphs:

 

please can someone at VM help me get this resolved? I'm at the point where I will take slower speeds from another provider over this anti-consumer omni-shambles of a company.