Harassment even wben payment arrangement is met is this legal

The worst company to deal with.On number of occasions i emailed sigma and advised them i am unemployed for 6 years i made a payment arrangement and ever since i have been keeping to my arrangement.I then advised them to email me since my phone doesnt allow calls or making calls i have access to emails only and texts they still call me non stop and request i call them back.I cant receive or make calls my phone is broken and im unemployed but i still make my monthly payement arrangement.I am sick and tired of the harassment from sigma.I use your customer service email address that your company provided.I requested for a consultant to email me years have gone by and nobody ever did.I suggest that a consultant email me and read my review my phone doesnt work i have access to emails only and i have emailed your company proof of payment like i always do so why are you harassing me still. my email address ***