Yes, that is the correct way of writing the message. Nothing wrong there from Cell*C.
The only thing they need to fix is to use the same system used by both 8.ta and Vodacom where you know that a call back has been delivered or not immediately.
vodacom & mtn they use simply to understand phrases, e.g please call 'number'. who is 'them' here? whether im write or wrong, i dont like please call me by cellc, it is unclear & not simply.