Delux pulsating sprinkler is anything but that!

What a HUGE disappointment!!!!! 5 weeks ago I purchased a garden master "delux" pulsating sprinkler with a 2 year guarantee from Builders Warehouse. After only 4 weeks the sprinkler stopped pulsating. Thinking this was a one off defective product took it back to builders, got a refund and purchased another one. After only 1 hour of use that sprinkler also stopped pulsating. Will be taking that back today and buying another brand. How can you offer a 2 year guarantee 9n something that does not even work for 2 hours!!!!!