how to top up mobile partner dongle credit

[inquisitor]

Vodacom is Vodafone's South African subsidiary, who have their own USSD codes. That's why *100# does not work with your British Vodafone SIM.

For Vodafone UK use the following USSD codes:
to check credit : *#1345#
to top up : *#1345*VOUCHER NUMBER#

The dongle's phone number acutally is, as its name implies, the phone number of the SIM card, not the IMEI or IMSI.
However the only thing you need now it a top-up voucher, whose code you need to submit by USSD as given above.