Service Cut Off Unexpectedly

I'm currently overseas and my mobile phone was off for 3 days and after charging my phone I discovered my phone had no service. After contacting customer service I was informed my account has been deleted. This leaves me financially stranded while out of South Africa as my internet banking requires OTPs which now I'm unable to receive. What I need is my account reactivated and to retain my old phone number. Please can you resolve this for me as soon as possible