Relentless harassment from Virgin Active N1 City

A few months ago I visited Virgin Active N1 City for a tour through the facility and get info on memberships etc. This was done and I left telling them I will think about it. They first tried their sales persuasion to get me to sign but I resisted. For weeks I got calls asking when am I going to join and then try to persuade me to join. I got irritated with this and told them not to bother me. Should I change my mind about joining I will call them, they must not call me. This did not stop them calling me every other week. 2 weeks ago was the last straw and I angrily demanded they lose my number and never call me again. Today I got another call - I have now had enough. I told the guy this is harassment and that I will lodge a complaint. I am sick and tired of being harassed by them. Not even Estate Agents are as persistent at harassing people like they do. They have absolutely no respect for boundaries and just ignore your instruction to not contact you again. Every time it's a different person calling. I will now never consider Virgin Active should I want to join a gym. I demand that they stop harassing me!!