URGENT change Kitchen Mixer Tap cartridge

[Erik2426]

I do not know how to open the cartridge place. I need to change my Kitchen Mixer Tap Dual Spout with Pull Out Spray cartridge.
It is like Rangemaster Aquatrend Spring Kitchen Mixer Tap with Pull Out Spout:

Rangemaster Aquatrend Spring Kitchen Mixer Tap with Pull Out Spout

Shop the Rangemaster Aquatrend Spring Kitchen Mixer Tap with Pull Out Spout at Tap Warehouse with free delivery over £250* and 0% finance available**

www.tapwarehouse.com