The Sale of Goods and Supply of Services Act 1980 covers this area. Unfortunately there are no set time frames under the act which the seller has to abide by when repairing the product. However it should be do e within a reasonable time. When they call you back tell them that 4 weeks is an unreasonable amount of time considering that the item is an item of everyday use and you are experiencing considerable inconvenience as a result of this inordinate delay.
Tell them if they are unable to repair it you will be demanding a refund so you can purchase a new washing machine elsewhere. If you are not satisfied with the way the retailer is behaving you can take them to the small claims court. It costs about €15. The threat of this might hurry them along. The National Consumer Agency are great for giving out info like this.
Give them, or get from them a confirmed deadline for repairing the product, and say you will bring them to court if this deadline is not met.