Having worked for BT for over ten years I can assure you that is not the norm. If there really is a network issue then they would never charge early termination fees - in addition, shortly before I left the company Ofcom had introduced minimum guaranteed access line speeds (I think that's the right term for it) which means that if the broadband download speed is less than you were advised at point of sale then you could also terminate without penalty.
ETCs are only supposed to be raised when the customer chooses to end the contract early.
Ho Hum
As a supplier of telecoms I have on a few occasions found BT Business to not be behaving very ethically with regard to charges
4 Examples
BT Local Business falsely signed up a customer for a contract renewal on a rather expensive set of ISDN lines (cost 7K )
Neither BT Local Business nor BT Business could produce any evidence that this renewal had been agreed by the customer
Escalated to BT Exec office who told the customer that they would be held to contract as their accounts would have received an invoice that would have said 5 year contract in tiny letters on a bill and this meant that the customer had accepted
Retracted this when I said I would be reporting what I believe was fraudulent behaviour from BT Local Business to Action Fraud and Ofcom
In our old office the line which was supplied by the landlord was ceased which in turn ceased the broadband
We had ETC of £900 which was waived if we took out a new 12 month contract which we did
This did not stop BT from carrying on harasssing us about the £900 non existant debt
A polite email to Gavin Patterson the CEO at the time asking if he was aware of FERGUSON V BRITISH GAS TRADING LT got the harassment stopped and 6 month free broadband
Last week we have a number port going through
BT write to customer to confirm that the port is ligit.
When customer calls BT to confirm BT tell the customer that someone has cancelled the port but are unwilling to supply any details of who or when
The number is still not ported
A customer had ADSL and wanted to upgrade to FTTC mid term
I spoke to 4 reps
3 said it was a 2 year minimum contract
1 said it was 12 months which turned out to be true
(So a porkie telling rate of 3 out of 4 in BTs favour !)
On the plus side
They are getting better as other posters have confirmed
They gave me 2 years of FTTC for £8.00 per month
They have always been fair on compensation when they have messed up
They are still many times better than Talk Talk