Flying from Lansaria to Capt

I booked a flight to capt< i later changes it to dbn and such a change was effected. a day before the flying date i did get the reminder that i shall be flying the following day. I later gotten an email telling me that such flight has been cancelled and i expect a call for changes to be made. I then got a call from a lady who knows nothing about customer care and she told me that my booking doesn't exist yet i did get the mail from them as well as the one informing me of the cancelled flight. Someone out there kindly help on how to go with the matter.....