Personalised service for 3,000 clients

How am I supposed to deliver personalised service for more than 3,000 clients? I'm writing this not because I have an answer, but because I need one.

I want to begin this post talking about personalised service, because I  have realised that the few clients that have a personalised relationship with our company have become more loyal to us, this is the reason why I would like to establish that sort of relationship with our 3,000 clients.

What we have done to establish a closer relationship with our clients is to base our communication with them through telephone calls. We have 3 types of calls at the moment, first we call all our new clients to welcome them and make sure we have the right contact information; second, we call the clients that decrease their transaction level; and third we call the top 40 clients every week.

I have made some of these calls myself, and I have found that the clients like us to call them. The phone calls are useful to us as well, since we receive valuable feedback on how our service is delivered and it helps us to make our clients understand when we have problems delivering our service to them.

We have some technological tools that allow us to deliver messages to our clients through the web site, but I don't feel it like a proper communication channel, I feel it like a monologue channel instead. My problem is that we don't have the resources to call 3,000 clients every week and I would like the clients to feel they matter. Any creative suggestions???