Quoting another shop's price is one of the most ineffective ways to bargain. If I were the shop owner, I will also say go to that shop and buy lah. Makes sense, what. If you feel the other shop provides a better deal, then why are you even in my shop?
exactly. You admit that you prefer to buy from the high price shop BECAUSE the high-price shop has something that the other shop doesn't. It's a self-contradictory argument in most cases. Think yourself why you must ask one shop to drop the price to the level of the other shop without buying straightaway from the cheaper shop.
Shops with better service may employ more salesmen or simply pay their salesmen better so they aren't grumpy and non-responsive. Or maybe they exchange things easily, have better after-sales service and have to incur more overhead costs with they have to recover from the pricing of things they sell. It doesn't make much sense to ask one shop to sell at the price of another shop.