At least one object must implement IComparable. - Sorting a GroupedCollection with Linq

I have the following structures as example:

class ServicesGroup : IServicesGroup, IComparable
{
      public string CityName { get; set; }
      public ObservableCollection<Service> Services { get; set; }
      public int CompareTo(object obj)
    {
        ServicesGroup sg = (ServicesGroup)obj;

        return String.Compare(this.CityName, sg.CityName);
    }            
}

I am trying to sort my collection of Services at each group by its [ServiceId] (ascending and descending):

tempCollection = new ObservableCollection<object>(collection.OrderBy(x => ((ServicesGroup)x).Services.OrderBy(y => y.ServiceId)));

My Service class implements IComparable as well:

I tried both
public class Service : IComparable, IEquatable
public class Service : IComparable<Service>, IEquatable<Service>

Example of my Service class:

public class Service : IComparable, IEquatable
{
            public string ServiceId {get; set;}
       

        public string ServiceType {get; set;}
           
            public int CompareTo(object obj)
        {
            Service s = (Service)obj;

            return String.Compare(this.ServiceId, s.ServiceId);
        }
       
            public bool Equals(Service other)
        {
            if (this.ServiceId.Equals(other.ServiceId) && this.ServiceType.Equals(other.ServiceType)) return true;
            return false;
        }            
}

When I try to run my linq I get the following error:

Additional information: At least one object must implement IComparable.

I can not access the [public ObservableCollection<Service> Services] for some reason. What am I missing here?