Although i congratulate you Paul on your stance,i would proceed with caution as i have come across a thread on here before,when the player complained for not receiving the credits,and threatened to go down the same route as you have said you will be doing.Only to find on a daily basis that the credits he had amassed from surveys was being taken back off him.Basically saying you threaten us we'll hit you where it hurts.
On another note i noticed that 1 of the posts here was from my offers.In my experience with these i got paid out on the 1st 1 from them,but all subsequent ones that i have done through them i haven't been paid.So i was thinking maybe you only get credited once by each site that are offering credits.
If you have £10 spare then at the moment Paddy Power are offering some good 1's.Just deposit £10 on their bingo site or games site and get 4.900 credits.Also if you have a smart phone there are loads of free download apps which pays credits.
Hope this helps.
Russell