old messages being sent repeatedly

Can you please advise - my old messages are being sent repeatedly.

I use Internet Explorer on my lap top at home and use my Samsung Galaxy S2 on my mobile through
Virgin network.

My old messages are being sent repeatedly like every 6/7mins.  However I don't think they are being recieved.

How do I stop this from happenine.  I did ask support and they asked me to contact mobile forum.

Please advise

thanks

Andrea