Right.... I've tried that and I've now paid £3.17p for 50 more credits.
Before I clicked on the 'Buy now' icon it said I had 176 left. This figure hasn't changed and after reloading Farm Town the amount of farm cash hasn't gone up so I'm obviously doing something wrong. Sorry to be a pain but could you explain simply how to get the credits onto Farm Town? I daren't click on anything now in case I've got to pay some more money.