I had still not received a response from my emails so I tried ringing again today on the 150 number. After a few minutes ("press 1 if your dog has died, press 2 if you like Jaffa Cakes") I managed to actually get through to a human being at Orange.
I explained to the Gentlemen that there was no way on God's Green Earth that I had used the data charges that were appearing on my account and I was then informed that my Handset (HTC Wildfire S) is actually capable of connecting to the internet on its own accord and that other people have enountered similar problems to myself.
I explained there was no way I was paying for something I hadn't used and that I'd been a customer for many years etc etc and eventually they agreed to fully credit all data charges on my account this month.
They have also given me free internet usage for a month as way of an apology.
I should add that I have added a bundle to my pack starting next month so this may have gone some way toward me getting a successful outcome. The bundle is only £5 a month so I thought it was worth it for peace of mind (it was either that or I could have them completely bar internet usage on my phone so I was never able to access it and no data charges would ever be applied).
I do like to use it from time to time so I thought for £5 a month it was worth it.
I will be keeping an eye on my bills as usual though, just in case.