Try: 'tie-up' or 'bond(ing)' . . .

Thanks. I did consider those options, but I'm sure that there is another phrase that marketing professionals use to describe this situation. You see it in business plans that include a strategy to create this "the customer _has_ to come to us" situation. I'll feed back if I find it.

"Plaintiffs continue to retreat from their tying claim," the brief states. "Although they pay lip service to the notion that Windows and IE are 'separate products,'...

combining?

Hi Bob (GB)
Try .. 'the customer is obliged' to go to ........

p.s I am an (English) English teacher in Germany !

...systems tie the customer to the manufacturer's repairs and maintenance services

...lock the customer in... could also work