I am unable to buy/load SMS/Data bundles by dialing 141/555 from my handset (even though I do have out of bundle airtime).

The options available when I dial these numbers (141 and/or 555) are:
1. Bal Enquiry
2. Load Airtime
3. Price Plan and Reward Info
0. Help

I have already called 173 for help but they keep on transferring me around. I am on Anytime Hybrid (TopUp) package with a different SP (not MTNSP).