Not willing to give cancellation letter

Since 5 May 2015 I have been requesting cancellation letter and I told every consultants that I have spoke to all the four days that the reason I need to cancel so I can join company group medical aid and as it was the last day on the 6th for me to submit this I won't get paid. I was disappointed when I was told I needed to cancel momentum as it was not part of the group scheme but after these few days I'm really happy I don't have to deal with momentum as there service is not up to standard really disappointed that I won't be getting paid because of the slow service of momentum and the sad part is the directors employ ppl who don't do their jobs on time.