Purchasing an inexpensive charger might ultimately be more costly; I would recommend opting for a product offered by your energy provider to ensure reliable support in case of any issues.
If your energy provider does not present a favourable offer, simply switch to one that does; it is not as if you are experiencing a complete charger malfunction that requires immediate resolution.
Examine the offerings of EDF, Octopus, and others, then conduct a comparative analysis of their energy tariffs, including the daily fee (I utilised an Excel spreadsheet for this, and it clearly indicated the most advantageous option at that time; I am uncertain if it remains so and need to reassess.)
I would dedicate some time to exploring all your alternatives; it may be somewhat tedious, yet it is quite gratifying in numerous ways when you can distinctly observe your savings.
If you wish to transition to Octopus, I possess a referral code that will provide us each with £50 in credit.