Is a guarantor's position that a bank's breach of the 23rd June Agreement with the company's guarantors makes the guarantee void?

The guarantors say that the bank's breach of the 23rd June agreement with the company made the guarantees void. There is no foundation in the guarantees for that position. The guarantors simply guaranteed all present and future debts and liabilities and permitted the bank to deal with the company as it saw fit. The company borrowed and the bank advanced on the strength of the guarantees. There is no reason to insert in the guarantees a term not consistent with their tenor. That which cannot be done expressly (see Hawrish v. Bank of Montreal, 1969 CanLII 2 (SCC), [1969] S.C.R. 515, 66 W.W.R. 673, 2 D.L.R. (3d) 600) surely cannot be done by implication.