You don't need a separate id for the linking tables customerservices or customers_promotions, as there is a natural joint key in each case - customer_id with service_id in the first table and promotion_id with customer_id in the second table. Unless you declare these combinations unique, someone can sign up for the same promotion twice, for example. However sometimes a separate id is used to make further linking to another table easier.
Next, you have some attributes in one table that are in the table they are linked to. This creates lots of room for errors.
Accountdetails has an id of its own, then includes customer_id and service_id again - they are in the customerservices table already. If you use a separate id for customerservices, you do not need to have customer_id and service_id in accountdetails. If you use a joint key in the customerservices table, then you would use customer_id and service_id as the joint foreign key in accountdetails.
There is a balance in customer services and in account details - are they the same thing?
So re-think things a little bit and have another go. Any changes depend on whether you use a joint key or not in some tables.
EDIT Ah I too wondered about the username and password being in the other table, then forgot it.