Poor attention to emergency changes on my flight

Am an eDreams Prime member and I have been trying to change my travel date to the 11th February for 2 weeks. I wrote up to 5 emails with no success and the time is running out already.Am in distress thinking that I can loose my ticket because of their own poor service. I don’t know what to do next. I paid for Prime membership so that my unforeseen circumstances can be addressed quickly but am not benefiting from this expensive membership. Am in despair .