Afrihost/Vumatel promise speed but doesn't deliver

Good day. account nr:A*** My fiber line of 50mbs/50mbs have been installed on the 5th of October, but since then I've only had a service speed of 20mbs/10mbs. I've logged numerous tickets, but to no avail, and it doesn't get fixed., meanwhile I'm paying of a more expensive service, and don't get the delivery. ticket nrs: ISP-911428 ISP-919523 ISP-926408 EER-***7 ISP-927810 Im very disappointed with the service, and feel my correct service needs to be delivered, and i be reimbursed for the time on the incorrect speed. regards Ludwig