Lip sync issues when watching VOD

[Happyhotspur]

Whatever film I try to watch using VOD the film starts ok but gradually the lip sync just goes out but does anybody know what could cause this issue?

[crazed 9.6]

this should not be happening.

Are you using wifi connection?

[Happyhotspur]

No Ethernet wired connection

[crazed 9.6]

try an IPTV Reset at the service website.

Are you using these VODs thru a loaded USB file or thru the server URL or thru a reciever and its onboard players (like the Dreamlink or Buzz box) ?

[Happyhotspur]

Using it through my paid iptv supplier.
Have had previous issues with stuttering, buffering, jumping Catch up is almost impossible to watch Had a Z-Nano box but changed to a Mag256w1, yesterday whilst watching Football Swansea v Tottenham five times the matched stopped, twice it went back over what I had just watched, and its fast becoming impossible to watch a VOD supplied through their service.
They have continually informed me its my isp thats the problem and they are throttling however my isp company have insisted its not them and have changed my router and have also supplied me with a different iptv service for a trial which worked without a hitch and my current iptv company still insists its not their issue,
I am at my wits end to find out the real problem
I was with another provider without any issues except they stopped broadcasting the football matches I wanted to watch hence the change but not sure if I've made a huge expensive error
If all my issues are iptv provider then I will just have to bit the bullet and write the money off and find a more reliable provider but if its my isp company then I will change their service for a more reliable one, but am leaning towards the issue being iptv provider.
I thought about signing up for a few free trials to see if I get any issues that way to confirm whether its my provider or not.
sorry to go on but really am at my wits end with this