new use of telecom billing scam

I have just been reading on this forum about the Telecom billing scam several years ago, well it seems there is a new company trying the same scam, I recently rang a chat line that was advertised in my local newspaper the line started with a 0208 number and I was only on the line for just over a minute I didn't speak to anyone and there was no message to say how much the call cost. After making the call I forgot about it, then a month later I got a phone call from some one who tricked me into giving my name and address details, another month later and I have received an invoice saying I owe £75 for this phone call even though on my BT bill the number is listed as a landline number with no charge, the number they have given on the invoice is not the number I rang it is a 0044208 number with the remainder being my phone number the invoice is from a company called RMS with a PO Box address in Czech Republic though the postage mark on the envelope was from Germany, it stated that if the amount is not paid within 8 days I will be in default with the corresponding default consequences, it says the statutory value added tax is include in the invoice amount and RMS asserts the claim by way of factoring. I have not paid them anything and am scared at what they might do next.