I�m concerned to read this. It is �possible� that your sim card has been pirated. I believe it�s important to ensure your provider check this. Additionally, demand that they identify the �root� end to the call. This means to identify whether it�s a mobile or a land line.
Unfortunately, our nation is targeted for a large number of frauds. One is that you will see a local number, that actually auto-switches to a premium rate number, or which I think is in your case, a possible dial-back tracer, where they are picking up all the numbers you call. The reason I believe this may be the case is due to the �extra� number you allude to, which sounds like a number of Russian exchange numbers.
Indeed, contact OFTEL and OFCOM for advice. If the cost of these calls have been shown as minimum, with less than 10 seconds air time, the provider is bound to remove the call cost. Finally, ensure you are not accidentally dialling numbers through motion, by failing to lock your phone. I ran up a �210 bill three years ago, when my phone accidentally became unlocked whilst I was riding in a World War 2 jeep, across Moldova! My fault, my bill!
I wish you success in your endeavours
Fr Bill