This is the way it could work, to narrow down the list <free idea,wont ask for jack, I swear :) :

This i suppose is easy to pull off:

Please select type of company to pay your MPESA bill:

1. Technology
2. Electrical
3. Water
4. Banking
5. Food
6. etc etc

You select "4" = Banking. A menu is uploaded from the servers in whatever format - data or sms menu:

Please select bank:

1. Equete
2. Barclays
3. Cooperative
4. Stan Chart
5. That Bank with only one branch

You select "1" = Equete.

Please select what you wanna pay for:

1. Credit card bill
2. That loan you took for your car 4 years ago
3. Salary advance (though why would you wanna pay for this?)

Please enter amount: Ksh. XXXXXXX

VOILA !!!