I'm trying to use surface controllers to display a list of products. This is working fine however if I try to call this twice I get the exception:

@Html.Action("List", "Product", new { size = 10 })
@Html.Action("List", "Product", new { size = 10 })

A single instance of controller 'ProductController' cannot be used to handle multiple requests.

The way I'm using it is to call the Product list controller via a Macro so that the user can add a product list anywhere.

Controller:

/// <summary>
/// Product details controller
/// </summary>
public class ProductController : SurfaceController
{
    private readonly string uri = ConfigurationManager.AppSettings["uri:searchApi"];

public ActionResult List(ProductSearch request, int size = 10)
{
    string requestUri = "workgroups/?page=0&pageSize=" + size;

    ProductSearch search = SearchHelper.CreateSearch(request, null);

    using (var client = new HttpClient())
    {
        client.BaseAddress = new Uri(uri);
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

        // New code:
        HttpResponseMessage response = client.PostAsJsonAsync(requestUri, search).Result;

        if (response.IsSuccessStatusCode)
        {
            WorkGroupSearchResult searchResult = response.Content.ReadAsAsync<WorkGroupSearchResult>().Result;

            return PartialView("List", new SearchModel(this.CurrentPage, searchResult));
        }
        else
        {
            throw new HttpRequestException("Request failed: " + response.StatusCode.ToString());
        }
    }            
}
}

Any help would be much appreciated.