Don't know if you've already found the answer to this, but if you're ringing the 0344 338 8605 phone number, then it should be classed as a local call and part of your phone companies inclusive minutes, but best to check with your provider. I've used it and not been charged for it.
I'm with EE and this is what they said - "Many organisations use 03 numbers such as 0300, 0344 or 0345 as an alternative to more expensive 084 and 087 numbers. Calls to 03 numbers will cost no more than a call to a 01 or 02 number. This means calls to 01, 02 or 03 numbers will come out of your inclusive minutes."
Hope that helps.