********** Activity by Sigma SA

I have been getting sms from Sigma SA about an alleged Ismart debt, which I told them is non-existent. I have told Sigma SA to stop contacting me and they seem adamant to be in contravention of numerous legislative frameworks. The reference of the alleged debt is **********7 I have written them sms and emails, which they never bother to answer. I tried to call their 086 number, where am made to hold for the next available agent for ages. I have filled in an enquiry form on their website and told them any other attempt will lead to further steps being taken against their ********** activity.