IS MY TELCO ROBBING ME BLIND?

I have been using the same Telco for my prepaid mobile phone for the past 7 years and recently I have been receiving sms at an average of 1 per day which goes like this:
RM0.50. Sarah (Female Age:18) is inviting you to be her friend. Reply YES-581 or NO-581. See her at www.AMS.ac/u/hizli87 STOP? Reply STOP FRND."
For several months I did not know the implication of such an sms. I thought that if I didn't respond I would not incur any expense. However, when I went to the local Telco office to make enquiries and to find out whether they could do anything to stop such sms being sent to me, I was shocked to be told that each time such an sms was sent to me I was charged 50 sen. When I expressed shock that I was being robbed blindly and my Telco was not doing anything to protect me, I was told that I shouldn't have subscribed to this service in the first place. I pointed out to the lady attending to me that I am a senior citizen in my twilight years and sending sms was not my favourite pasttime and that the rare sms that I have sent have been in response to friends' occasional sms which would be few and rare. I did not subscribe to any "pimping service" nor have I lent my phone to anybody who would subscribe to such a service on my behalf and apart from my wife, who never uses my mobile phone, I don't have any teenage son or daughter living with me. I asked her why my Telco could not protect me from such spamming and was told that they were powerless to do anything. I was advised to reply to the sms by typing "STOP FRND". I did as advised and received the following sms in response.
"Free msg. Your subscription to Friends Requests has been terminated. Thank you for your patronage."
However, this did not stop 2 more sms to be sent to me immediately thereafter, offering me the friendship of 2 female companions, each sms costing RM0.50. I wonder how many people using mobile phones have been plagued by this costly nuisance. My Telco insists that I, or somebody using my phone, must have subscribed to this service by sending an sms to the company. I denied vehemently that I had done such a thing and also I had never loaned my phone to anyone who would do such a thing. I asked them why they could not take the necessary steps to protect their customers from being victims of such blatant robbery and suggested that probably the Telco was in league with the "pimping" company to rob their customers.