Yes, if there was dual representation, then both parties are the attorney's client and he owes the same legal duties of effective and loyal represenation to both. If the attorney is not discharging his professional obligations to you, you could look to file an ethical complaint about him; you might also first let him know that if he does not provide you the assistance and representation he is supposed to, you will take all appropriate legal steps to protect your rights, including filing a complaint if necessary. Possibly, that will motivate him to help, or at least to explain in a clear way, so it can be discussed, why he feels this is not part of his representation of you.