the response from Vodacom is:
output: OK +CUSD: 1,"31292042616c616e6365730a3229204275790a332920416c6c2034205
I do realize I'm late to the party, but do you need the Mikrotik itself to understand the USSD response (and maybe take some action based on the contents) or is it sufficient to make it human-readable?
Because the above is merely a hex-encoded ASCII, each pair of symbols 0..9,a..f represents one resulting symbol, so the translation done by any hex->ascii converter is
3) All 4 You
4) Just 4 You
10) Get 10% more
Instead of writing novels, post /export hide-sensitive. Use find&replace in your favourite text editor to systematically replace all occurrences of each public IP address potentially identifying you by a distinctive pattern such as my.public.ip.1.