ISP Speeds drop after using Airport Extreme.

Hi

We have had numerous problems with BT over the last 18 months since moving from ADSL to their Fibre Infinity Service (Fibre to CAB - Copper from CAB to ouse).

I do not like their Home Hub 3 (Router)that comes as part of their service, and prefer for many reasons to use my Airport Extreme.

We have had over 20 engineers out due to drops in speed from 20Mb to 2MB or less. They though they had fixed it on Satuday as it was

a phone connection from the home Master phone socket. Errors stopped on the line and we were back to 21MB again. Now, three days later and havng

used the AEBS again for two of them, our line has now dropped back to 2MB.

I want a guest network, so the day after the engineer had been I changed the home hub for my AEBS. The speeds remained unchanged for 24 hours and then dropped again. However, now using the BT Home Hub again and the still have the same slow 2MB speed!!

Could there be a problem with my AEBS?

Thanks in advance.

Matt