If there is enough length of hose, you can try cutting half a cm of hose off the end so you have unstretched hose over the plastic tank, sometimes the hoses will stretch a little, otherwise, like @thepartsfactory4239 said, higher quality clamps that can clamp more evenly.
Clamp the hoses before removal from the expansion tank. Keep them clamped until you have refilled the coolant. Then release clamps. This will save you from bleeding you're cooling system.
