Paying For 20mb Getting 2mb

Question

 BT sold my son 20mb Unlimited Broadband about Nov 2010, he told me the other week that his BB was very poor as every test he did came back with 2mb d/ld speed. So I tried the BT location site and put in his phone number - and the fastest connection speed there equipment can deliver in his area is 8mb.
 I told him he should call them and get it fixed out as they were charging for a service that BT's equipment could NOT provide. 
 Tonight he called me, he said he was in contact with BT but there line was that it didn't matter that he was only getting 2mb, the £29 odds they were charging was because he was getting Unlimited Download, surely that can't be right.
 The service they sold him and he signed up for was 20mb Unlimited, now while there can be dips in d/ld speed and you can't always get 20mb, but that should not fall below 10mb. The thing is BT's EQUIPMENT CAN NOT EVEN DELIVER 20MB IN HIS AREA!
The fastest they CAN provide in his area is 8mb, I can see now why his speed is down at 2mb. BT would have to Upgrade there junction boxes to handle/put through 20mb. 
Surely he has been paying to much and should be due a refund, as BTs equipment can not provide 20mb.
BT Phone Number Checker ..........
 Your broadband checker results
Broadband option Estimated connection speed When you can get it Action 
BT Total Broadband BT Total BroadbandYou can get fast and reliable broadband with speeds of up to 8Mb. 

Answer 1

 Distance from the nearest BT exchange, its in the village where he lives, I would say he's less than half a mile from it. 
 Tried another site and got this ..
Congratulations, you are in a broadband enabled area.
Click here to compare packages available to you.
However, there is another service on your phone line (e.g. ADSL, LLU, DACS, etc) that would prevent you from ordering a new ADSL connection.
The following services are available in your location:
BT Wholesale ADSL
BT Wholesale ADSL Max
Virgin Media (Cable)
And from another site what these can provide ..
BT Wholesale provides wholesale ADSL broadband products to most of the UK’s ISPs. ADSL MAX lines are enhanced versions of the standard IPStream / Datastream ADSL products and use Rate-Adaptive (RA) technology to dynamically find the best ‘stable’ speed for your line. It is capable of offering speeds up to 8Mbps download and 448Kbps (800Kbps business) upload, though most will receive far less.
 I think that says, that BT can not deliver to his home (no matter if the exchange was in his hall cupboard) anything higher than 8mb d/ld speed.