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The seat fee you should get refunded, so apply for that via the online link under Our Seating Policy in BA.com.
For the customer service side, which amounts to the aircraft switch and no IFE, then by all means complain via the webform. Before you do it, you may want to assess how many Avios would repair the damage. You are unlikely to be offered this, I would guess about 4k Avios per passenger will be offered, or a duty free voucher alternative perhaps. If this is insufficient your two choices are to reluctantly accept (and possibly use another airline next time) or to pursue BA for your original assessment, either via MCOL, CEDR or your credit card. There is more information about these options in the EC261 thread in the BA Forum Dashboard (though this isn't an EC261 case, the pursuit method is pretty similar).