Discovery Vitality Travel - another Discovery Fail

I have been trying to change a booking that I made through Vitality Travel before lockdown. I have emailed and phoned and what's app'ed since 9 June 2020. No-one is coming back to me. I understand we are all busy and stressed but I find it unacceptable that in three weeks I have had no response to my query and also am unable to contact anyone that can help me. I just want to know if I can move the flight I had booked. Please could you provide contact details of someone that can help me?