Poor service Gotogate

On changing my flight return date, using a flexi ticket, I was quoted an amount of R4000 and told to pay using the link so they could proceed. I immediately payed, got my receipt via email..but straight after that another email saying my request has been forwarded to their internal concerns. My ticket wasn't changed and they just said I must bd patient, they will get back to me. Everyday I contacted them and always told to be patient. A week before I was to fly, I once again contacted them, only to hear that they can change it, but will now need another R4100, as time has gone by and tickets are now more expensive. I was desperate and once again paid the money. This time I received a new itinerary. How bad is that!!!!! Who is to blame.. Gotogate or Swiss Air???