You should have a table of customers and one for rates. Then a junction table that links customers to rates, because rates are one thing, customers are another (their own tables) but customers can have several rates, thus the junction table. The junction might have customer id and rate id plus have a PK index (autonumber would suffice) of its own.
On a form, header section can have customer info (not rates) with a subform below that lists the rates. You should be able to add or edit detail records in the subform if you set the link Master/Child property so that the customer id of the junction matches the customer id of the main form.
You could also list rates in a listbox for each customer on the main form and forget the subform, but you would need a way to edit/add records. Main/sub form relationship is a common topic.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.