i need help for vaxhall corsa?

i have a problem with the cooling system of my corsa sohc engine it is overheating i have replaced the temp switch in the radiotor and ir was wotking but now the heat get up teh switch dosent kick in so it starts to overheat also now a new symptom is that some of the pipes feel slightly swolen but cool could it be the thermostat that isfaulty and could the cylinder head have blow?