Assist me with Bulk Marketing

We want to convert our ebay customers who make monthly purchases for their service plan's to off-ebay customer's through automatic reup via our brick and mortar store. They can still have the protection of paypal when they pay. I have tried to send out amils to all inviting them to let us handle their reup every month but I only got 3 out of 150 to choose that method. I thought about blast text messages...We currently offer a discount on the plan and thats why they buy from us on ebay. we thought about limiting their discount to 3 months then normal price would apply but that is too difficult to do on ebay, and we risk losing good repeat customers...what would you do?