F#, Timer and propperly removed ElapsedEventHandler

Question

I have a simple method that receives messages from bus, builds response and send it back, and it looks like:

let readFromBusAndSendRequest =
        let mutable timer = new Timer(float 10000)
        let OnTimedEvent (frameId:uint32, projectId:uint32, cabinId:byte) (bus:IBus) : ElapsedEventHandler = 
            new ElapsedEventHandler (fun _ _ -> 
                printfn "Publishing UM1 Request %A Frame %A" DateTime.Now framId
                //Create request                        
                bus.Publish<RequestMessage>(request, HubSubscriptionId))

        match this.Bus with  
        | Some bus ->
            let cabinetSubscribeId = sprintf "Project.%i.Cabin.%i" this.ProjectId this.CabinId        
            let busResponseFactory (response : BasicMessage) =
            match response.FrameType with
            | FrameType.SERVICE_LIST ->                        
                let serviceListResponse : ServiceListMessage = response :?> ServiceListMessage
                let isMessageValid = serviceListResponse.FrameWithoutCrc.IsValidCrc32(serviceListResponse.ResponseCrc32)
                match isMessageValid with
                | true -> 
                     publishAck bus (serviceListResponse, RequestedService.Unknown)
                     timer.Dispose()
                     timer <- new Timer(float 10000, AutoReset = true)
                     timer.AutoReset <- true
                     timer.Elapsed.AddHandler(OnTimedEvent ((serviceListResponse.FrameId + 1u), this.ProjectId, byte this.CabinId) bus)
                     timer.Start();
                | false -> publishNack bus (serviceListResponse, RequestedService.Unknown) NackRejectionReason.InvalidCrc 
           | false -> publishNack bus (serviceResponse, serviceResponse.RequestedService) NackRejectionReason.InvalidCrc 
         | _  -> printfn "OTHER SUPPORT"

    let handler = Action<ResponseMessage>(fun response -> 
          printfn "Response %A frame type %s response id %i" response.ProjectId (response.FrameType.ToString()) response.FrameId; 
          busResponseFactory response |> ignore) 

    bus.Subscribe<ResponseMessage>(cabinetSubscribeId, handler, Action<FluentConfiguration.ISubscriptionConfiguration>(fun sub -> sub.WithTopic(cabinetSubscribeId) |> ignore)) |> ignore

When I get a certain type of response(in this case SERVICE_LIST), I want it to attach an event to the Timer, and make it run each 10 seconds. All parameters needed are from message received from bus

As you see, I used a mutable timer because each time I press I receive new SERVICE_LIST message, an event is added but but not removed, and believe me I tried:

  timer.Elapsed.RemoveHandler(OnTimedEvent frameId)

Probably because frame id is different every time.

Instead of dispose, but it did not work; new events were just added but not removed. So is there a better way to conquer this mess?

I know it is because I create new event each time, but how to remove old one?