It's made them more competitive on some products, such as the Sony BDP-S570 3D Blu-ray player which is reduced to £183 (Amazon price is £180).
Other M&S deals include the Panasonic DMP-BD45 at £120, Sony BDP-S470 £160, Samsung BD-C5500 £128, Panasonic DMP-BD65 £136 and Samsung BD-C6900 3D model at £280.
There's also 20% off the Award-winning Sony BDV-E300 Blu-ray in a box system, down to £399, or the Sony BDV-E670W at £479.
As for TVs, you can pick up an Award-winning Sony KDL-40EX503 for £599, or a Panasonic TX-L32D28BS Freesat HD LCD/LED model for £665.
These and more deals are on the Marks & Spencer website.
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