Mweb disgraceful customer service

Slow internet speed only from 7pm to 10pm. Speed drops from 200Mbps to 5 to 20Mbps. Have open ticket since 15 October. Sent complaints no response although the say they will get respond within 48hrs working hours. Technical have passed issue to network engineers. Cannot get Technical manager to phone me. Phone every day to follow up on progress. They have assign senior tech looking after my issue, but he also doesn't respond. Need help in obtaining Operations manager email address or phone number.