Number deleted and I can't get it back, even though it isn't assigned to anyone

I went overseas for a year and now my number is blocked. I tried to log into the app while overseas to add airtime, but the app wanted an OTP so I couldn't log in. I visited a Vodacom branch today and they looked up my number. My number has been deleted but it isn't assigned to anyone yet. I phoned Customer Care and they also said that they can't do anything. This is a HUGE problem. I've been using this number on WhatsApp for my business in SA the entire time. It is on every flyer, business card, document and all current, new and old clients have it. I completely understand that I won't be assigned the number if it has already been assigned to someone else, but it hasn't. No one else has this number yet. So why can't I just get it back??? I'm SOO mad and this is causing HUGE issues for me. AT LEAST make no OTP for the app for people to keep their network going. This three month rule is really pathetic since people can travel for longer than that and I plan to travel again in the near future. So that means every time I come back to SA, I need to buy a new number!