Have you checked for “known network faults”? As well as trying the “check service,” weblink (at the top of this forum board), there is also a Service Status number - 0800 561 0061 - which usually tells you of more local issues down to postcode level (that might even not yet be listed on the Service Status web page) - that may give you more info. If nothing shows on there call it in and see what they say when they test your connection and if possible, get a fault reference number.
If you have a mobile and its VM call 150 if your on another service just call 0345 454 1111 for CS - its a national number so will be included as a free call in you "minutes" package.
If you have an old Hub and want to swap it then you could try the "free" SH1/2/2ac upgrade/replacement scheme - see the link below - as they are trying to get everyone onto Hub3/4's
If you get the - "Ooops - please call" message – then when you call CS, go through options 1,1,4,5 - to get through to retentions - you will get a UK based person who should at least know about the deal - no-one seems to have informed the "offshore" lot about it yet ! It may be that they think that you aren’t eligible and they will want to charge you - do not accept that - come back here.