Best Swap with "dead" UM

[inquisitor]

Regarding SIM4travel, which I purchased, you should mention the network service fee of £0.39 per day of active use:

Network Service Fee – on each and every day that the service is used for inbound or outbound calls and outbound SMS, the customer will be charged a daily fee, (this fee is based upon each period of 24 hours from midnight to midnight GMT). The customer will not be charged the daily Network Service fee when there has not been an inbound or outbound calls and outbound SMS in a 24 hour period.

The minimum topup amount is £20, which you'll need to add in order your SIM to be able of receiving calls and of course place outbound calls and send texts.