Hi Barry,
That seems an extortionate charge, as does the 20 per month (for a special reward account?)
Is it definately a 150 charge and not a repayment of going over the limit.
Have either of you spoken to the bank in a calm but firm way to say that this is the first (I'm guessing) time that this has happened due to the non receipt of funds or something and ask them to not charge it on this occasion.
£150 is 7.5% charge per month (on 2000) which is an extortionate 138.2% APR (I hope I've calculated that correctly, it's a minimum of 90%)
Have they threatened to come round and break your legs too?
I'd get on the phone to HSBC to get to the bottom of it.
Good Luck
Sparky.