No help from Discovery on debit order amount being higher than policy schedule value

I have been trying to get feedback from Discovery Insure, via my intermediary, since 28 Feb 2018 with regards to premiums I have been getting charged which are different to my last policy schedule. We have together struggled to get an answer or any commitment at all to addressing the query. My intermediary has even gone up to management level with zero feedback. We do not know how to handle this query any more. I am completely disappointed with the service. This is the second time I have been getting charged more than my policy schedule, but the last time it was resolved in about 1 week and the overcharge amounts paid back to me. This time, I can't even get them to look at the issue at all.