49A1 ; 49B1 [Buyer's right to avoid contract, grounds for avoidance: fundamental beach; Buyer's loss of right to declare avoidance after delivery: failure to avoid within periods specified in art. 49 (five weeks after delivery of inadequately repaired goods held to constitute "reasonable time" for avoidance];

84B [When avoiding the contract buyer must account to seller for benefits from goods (no benefits found to be present]