Vodafone Line Switch Follow-up Not Given, Where is Help?

I attempted to switch my second line to postpaid through the Vodafone Yanımda app, choosing an offer. Despite receiving an SMS, there was no follow-up. After challenging attempts to contact customer service, they confirmed my chosen package was canceled and assured a refund, which never happened. Subsequent calls to customer service revealed the package was removed, and I couldn't reapply. Despite daily reminders from Vodafone to switch to postpaid, self-initiated efforts are unhelpful, leaving me frustrated and without resolution.