Vodacom re-allocated telephone number in use for over 15years

My father was overseas for 3 months. They have returned just to find out that VODACOM has allocated his number to someone else because his number was not used in 3 months time. Although 3months will only be tomorrow 1August. THey already contacted vodacom on 30July to ask why they cannot load money on his account, and then they where told "sorry it was re-allocated" Who gives VODACOM the right to do this? SO imagine the chaos, when people phone this original number and get through to somoene else? All the personal smsses that go to that number. How can Vodacom allocate numbers just like that? What is going on with Vodacom? Seems they are just doing whatever they want and does not care about the consumers. We URGENTLY require someone in a position to assist to contact us from Vodacom please