huawei pocket wifi -top up?

[HelenP]

bought the above a few months ago, havent used it (long story), credit/data/package expired end march & i need to top up on PAYG cos will need it for the next few months. guy in shop put the sim in & i have no record of the phone no attached to the sim. is it as simple as buying a new sim (eg PAYG £10 4gb - the mention of text & minutes is confusing me & if i do this, how do i get the 5x & £10 offers cos i cant text from the device...?) or is there another way i can get the phone no of the sim so that i can top up online (would i get the unused data carried over that way?) i dont have a phone that the sim will fit into - tried that one  , any advice on how i can top up gratefully appreciated. thank-you Helen x

[MI5]

@HelenP 

Your number should be on the sim holder and you can top up here https://mbb.o2.co.uk/Refresh/NewUserSignin

Logging into your mifi control panel should also give the number.

[HelenP]

I dont have the sim holder (guy in shop did it) & have no credit to use it's wifi to log into anything... ?

[MI5]

Connect the device you are using to the O2 Pocket hotspot. Either using WiFi or using USB.
Open an internet browser. If the O2 Pocket Hotspot homepage doesn’t automatically open type 192.168.0.1 into the browser search window and click enter
In the Advanced Setup password box type “admin” and press Login
Select Yes on the warning