Some refunds were made through settlements while others resulted in lawsuits. See, e.g., Cities Service Gas Co. v. Columbia Fuel Corp., 52 Del. 262, 155 A.2d 879 (1959). Our Commissioner took these refunds into account in computing the "net amount paid" from 1954 through 1957.

The ruling of the Court below is challenged by Western on several grounds: (1) the record does not justify a finding of business compulsion and there should at least be a trial before its existence can be determined; (2) payment of the excess was a voluntary one which cannot be recovered, or, at least, it cannot be held involuntary without further proof; (3) the excess was paid by mistake of law for which no recovery may be had; (4) there has been no unjust enrichment because Cities was reimbursed by an increase in the rates paid by its customers and has therefore lost nothing; (5) the action is barred by the statute of limitations. Although in the arguments before us much stress has been laid upon the theory of business compulsion or duress, that theory of recovery is not even mentioned in any of the opinions of the lower Court. At one point, in discussing the propriety of summary judgment, that Court refers to its prior holding in Cities Service Gas Co. v. Columbian Fuel Corp., 2 Storey 262, 52 Del. 262, 155 A.2d 879, as being dispositive of many of the arguments made in this case. As we read the Columbian opinion, aside from the matter of jurisdiction, it deals primarily with a determination of the true "filed" or effective rate, counsel having conceded that Columbian could not retain any money paid in excess thereof.

Defendant also maintains that Harris would be the only proper party defendant in a suit for restitution and that in any event Harris is an indispensable party to any such suit. The basic facts upon which plaintiff's claim rests are almost identical to those presented to this Court in a number of other cases including the case of Cities Service Gas Company v. Columbian Fuel Corporation, 2 Storey 262, 155 A.2d 879 (Superior Court 1959). The only pertinent unique feature of the case at bar is the agreement between Hugoton Plains and Harris whereby Harris was given certain rights and duties in order to secure the loan from the insurance companies to Hugoton Plains. Defendant's motion for summary judgment is based entirely upon this agreement and the relationship of the parties with Harris in view of the agreement.