MTN phoned me to upgrade my current package at “No extra” cost

MTN phoned me to upgrade my current package at “No extra” cost. My bill was in fact higher this month. When I phoned them, after the 3rd time I eventually got through to them. They advised me that they are unable to assist and that I need to phone the “sales department” When I phoned the number MTN gave me for sales, I got through to a 3rd party that does sales on their behalf. This company just said we need to reverse the upgrade and ask MTN for the refund. No one is taking ownership for the false upgrade they promised and we are left with all the admin work to resolve their error.