Calling function with two template parameters

I am having a problem calling a template function with two template arguments.

I have a class and the class accepts objects of two different types. I don't know the types yet, so I left them as template parameters. I then store the objects in wrapper classes. In the end I want to be able to call a templated function with two template arguments, that takes my two objects. But I am perplexed at how to do this.

Here is a stripped down version of the code to explain my problem.

template<typename A, typename B>
void someTemplateFunction(A a, B b);


class Problem
{
  private:
    class WrapperA
    {
      public:
        virtual void doSomething() = 0;
    };

    template<typename A>
    class ConcreteWrapperA : public wrapperA
    {
      private:
        A a;
      public:
        ConcreteWrapperB(A b_) : a(a_) {}
        virtual void doSomething();
    };

    class WrapperB
    {
      public:
        virtual void doSomething() = 0;
    };

    template<typename B>
    class ConcreteWrapperB : public wrapperB
    {
      private:
        B b;
      public:
        ConcreteWrapperB(B b_) : b(b_) {}
        virtual void doSomething();
    };

    WrapperA *a;
    WrapperB *b;

  public:

    template<typename A>
    void setA(A a)
    {
      a = new ConcreteWrapperA<A>(a);
    }

    template<typename B>
    void setB(B b)
    {
      a = new ConcreteWrapperB<B>(b);
    }

    void call_someTemplateFunction(); // ??????? How do i do this?
};