Having read through the agreement, it only states which appliances must be replaced by the landlord, there isn't a time period specified.
Would it be reasonable to request a discount on the rent if the issues are not resolved within the next 7 days? As it stands we currently have no alternative way to cook or heat food so this will mean further expense.
Regarding the quality of the replacements, the oven which is currently broken was a replacement before I moved into the property. The dial which has now jammed has always worked back-to-front to the actual oven setting, i.e when the dial indicates the highest heat setting, the oven will switch off and vice versa. So although technically the oven has worked up until now, there has always been this fault present. The reason I enquired after the quality of a replacement was to try and prevent getting another appliance with these faults and simply being told that it is functional.