Rear bulbs and poor connection

I'm not a mechanic, but I like fixing my friends cars. So, what can I say about this work? I would like to replace the entire light, but for now, my friend wanted to know if there's a cheaper option. I'd like to ask if there's any advice on making a better connection. This is an ugly and short-term fix - I have to replace the same bulb every month.

Edit: Peugeot 207 1.6 16V Petrol, 2007.